Strengthened cellular concrete compositions and method of making

ABSTRACT

A cellular concrete composition having improved strength consisting of hydraulic cement, water and at least one alpha, beta-unsaturated dicarboxylic acid such a maleic or fumaric acid. A method is also provided comprising preparing a cement paste containing hyraulic cement and water, mixing the cement paste with a bubbled frother solution containing at least one alpha, beta-unsaturated dicarboxylic acid and optionally an alkylene glycol and/or a nonionic surface-active agent, and casting the mixture in a mold to solidify.

BACKGROUND OF THE INVENTION

The present invention relates to cellular concrete compositions which are strengthened by addition of polycarboxylic acids, and the method of making such compositions. More particularly the present invention relates to light-weight cellular concrete, the strength of which is improved by addition of polycarboxylic acids such as maleic and fumaric acid or their combined use with alkylene glycols such as ethylene glycol and/or nonionic surface active agents such as polyethylene glycol, and the method, in which cellular concrete is produced by mixing a cement mortar or paste with a bubbled frother solution containing polycarboxylic acids or together with alkylene glycols and/or nonionic surface active agents.

The light weight, heat insulation, fire resistance, and sound insulation of cellular concrete have allowed it to find a definite niche in the field of building materials.

The process for producing cellular concrete is generally divided into two: (1) to make a cement mortar foam in a form after mixing all the ingredients and (2) to mix a cement paste with a bubbled frother solution, followed by casting this cellular concrete paste into a form. The latter method is widely used since it can make it easy to manufacture the desired form of cellular concrete. However, this procedure has a difficulty to control the flow of aerated concrete slurry or to cause defoaming during the mixing.

For this reason, the use of surface active agents or decomposition products of keratin-type proteins as frother have been proposed. And also, Japanese Patent Publication No. 61-5673 provides processes in which cellular concrete is produced by addition of anionic surface active agents during or just after mixing a cement mortar with a bubbled, high-viscous frother solution. These methods, however, are also unsatisfactory since they do not give cellular concrete manufactures having a sufficient mechanical strength.

SUMMARY OF THE INVENTION

In accordance with the present invention, cellular concrete compositions are provided that are strengthened by addition of polycarboxylic acids such as maleic and fumaric acid or their combined use with alkylene glycol and/or nonionic surface-active agents such as polyethylene glycol, and methods of making such compositions, with excellent properties, as compared with the conventional frothers or methods which are provided by Japanese Patent Publication No. 61-5673.

Exemplary polycarboxylic acids include maleic acid, fumaric acid, itaconic acid, succinic acid, oxalic acid, tartaric acid, sebacic acid, malonic acid, phthalic acid, terephthalic acid, trimellic acid, and pyromellic acid. Exemplary alkylene glycols include ethylene glycol, propylene glycol, and butylene glycol. Exemplary nonionic surface-active agents include polyethylene glycol, polyethylene glycol alkyl ether, polypropylene alkyl ether, polyethylene glycol fatty acid ester, sorbitan fatty acid ester, and fatty acid monoglyceride.

Cellular concrete compositions of the present invention are manufactured by mixing a cement paste with a bubbled frother solution containing polycarboxylic acids or together with alkylene glycols and/or nonionic surface active agents.

In this case, aggregates such as sand and silica may be used in combination with cement. And also, hydraulic cement such as Portland or alumina cement is commonly used.

In addition, other conventional additives for cellular concrete, such as thickeners, water reducing agents, other surface active agents, and binders can be employed.

The following Examples are illustrative.

EXAMPLE 1

Production of cellular concrete manufacture containing maleic and fumaric acid and ethylene glycol

Into 3600 g of Portland cement (Nippon Cement) was added 2000 ml of water and the mixture was agitated to form a cement paste. In the meantime, 5 g of maleic acid and 3 g of fumaric acid and 2 g of ethylene glycol were dissolved in 190 ml of water. The mixture was aerated by a bubble generator, to form a frother solution. The above cement paste and frother solution were mixed and agitated to form a cellular concrete slurry. The slurry was casted into a form. The concrete in the form was allowed to stand for 28 days at room temperature. The resultant cellular concrete manufacture was taken out from the form and cut in the form of 4×4×16 cm³ plate. The found specific gravity of the product was 0.58, giving an indication that the content of blowhole was 66.5 vol %.

The following examples represent preferred embodiments of cellular concrete compositions in accordance with the invention.

EXAMPLE 2

Cellular concrete compositions were prepared using frothers of the invention and two of the prior art, and having the following formulation:

    ______________________________________                                         Ingredients  Parts by Weight                                                   ______________________________________                                         Portland cement                                                                             3600                                                              (Nippon Cement)                                                                Water        2190    (2000 ml for cement paste and                                                  190 ml for frother solution)                              Frother      10                                                                ______________________________________                                    

                  TABLE 1                                                          ______________________________________                                         Example No. Frother                                                            ______________________________________                                         Control 1   Polyvalent metal salt of synthetic high                                        polymer (Pafoam EPM-I, Kao Sekken)                                 Control 2   Decomposition product of Keratin-type                                          protein (Foamix CII: Hamano Kogyo)                                 Example 1   maleic acid                                                        Example 2   maleic acid and fumaric acid                                                   (7:3 by weight)                                                    Example 3   maleic acid and fumaric acid and ethylene                                      glycol (5:3:2 by weight)                                           Example 4   maleic acid and fumaric acid and                                               polyethylene glycol (5:3:2 by weight)                              Example 5   maleic acid and fumaric acid and ethylene                                      glycol and polyethylene glycol                                                 (5:3:1:1 by weight)                                                ______________________________________                                    

Cellular concrete manufactures containing frothers shown in Table 1 were produced in the same manner as described in Example 1. The aeration of the frother solution was regulated to make the specific gravity of the final product to be 0.58±0.02, which corresponds to 66.5±2.3 vol % of blowhole. Plates of 4×4×6 cm³ were cut off and subjected to mechanical strength tests. The results are shown in Tables 2 and 3.

                  TABLE 2                                                          ______________________________________                                                       Compressive                                                                               Coefficient of                                                      strength   contraction                                           Example NO.   (kg/cm.sup.2)                                                                             (×10.sup.-4)                                    ______________________________________                                         Control 1     16         18                                                    Control 2     16         18                                                    Example 1     20         13                                                    Example 2     21         12                                                    Example 3     22         11                                                    Example 4     22         11                                                    Example 5     23         10                                                    ______________________________________                                    

                  TABLE 3                                                          ______________________________________                                                        Young's  flexural                                                              modulas  strength                                               Example No.    (×10.sup.-4)                                                                      (kg/cm.sup.2)                                          ______________________________________                                         Control 1      0.8      1                                                      Control 2      0.8      2                                                      Example 1      1.4      3                                                      Example 2      1.4      4                                                      Example 3      1.5      4                                                      Example 4      1.5      4                                                      Example 5      1.6      5                                                      ______________________________________                                    

The improvement when using the frother of the invention as compared with the Controls is evident from the above data.

Since many embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited by the specific examples except to the defined in the following claims. 

What is claimed is:
 1. A cellular concrete composition having improved mechanical strength consisting essentially of hydraulic cement, water and at least one alpha,beta-unsaturated dicarboxylic acid.
 2. A strengthened cellular concrete composition according to claim 1 in which the alpha,beta-unsaturated dicarboxylic acid is maleic acid.
 3. A strengthened cellular concrete composition according to claim 1 in which the alpha,beta-unsaturated dicarboxylic acids are maleic acid and fumaric acid.
 4. A strengthened cellular concrete composition according to claim 1 in which the composition further contains an alkylene glycol.
 5. A strengthened cellular concrete composition according to claim 4 in which the alkylene glycol is ethylene glycol.
 6. A strengthened cellular concrete composition according to claim 1 in which the composition contains a nonionic surface-active agent.
 7. A strengthened cellular concrete composition according to claim 6 in which the nonionic surface-active agent is polyethylene glycol.
 8. A strengthened cellular concrete composition according to claim 1 in which the composition contains an alkylene glycol and a nonionic surface-active agent.
 9. A strengthened cellular concrete composition according to claim 8 in which the alkylene glycol is ethylene glycol, and the nonionic surface-active agent is polyethylene glycol.
 10. A strengthened cellular concrete composition according to claim 1 in which the hydraulic cement is Portland cement. 